The PHPT research group was created in 1996 in Thailand, with the mission to develop strategies for preventing mother-to-child transmission of HIV, and methods of treating AIDS that could be integrated in the existing health care system in order to reach the populations who needed it most. The collaboration between the clinical trial unit, 37 public hospitals and the Ministry of public Health resulted in the completion of two major PMTCT studies that form the basis of the WHO and Thai national guidelines on PMTCT. Following previous collaboration with PACTG, the PHPT-CTU will continue to address outstanding issues that have been targeted by the IMPAACT leadership network. Within the context of rapid scale up of antiretroviral treatment programs in Thailand, PHPT has started a treatment monitoring strategy trial (PHPT-3) and organized a structured follow up of a large cohort of patients on treatment, and strengthened the involvement of the communities in these research activities. Therefore another area of focus for the PHPT CTU will be optimization of treatments in adults and adolescents. The organization of PHPT has demonstrated its ability to successfully conduct large clinical trials. The PHPT group has selected the 10 strongest clinical research sites to implement international studies with the leadership networks. These sites have access to large affected populations and have the expertise and infrastructure to carryout these studies, as well as contributing to the research agenda of the networks. The participation in the networks will add to the existing international collaborations to provide an environment conducive to the promotion of new investigators and clinical research staff in Thailand to sustain HIV research efforts. The research agenda to which the PHPT-CTU intends to contribute will have a major public health impact not only in Thailand but also for all communities affected by HIV. The sites participating in this research are Bhumibol Adulyadej Hospital, Chonburi Hospital, Hat Yai Hospital, Maharaj Nakorriratchasrima Hospital, Nakhonpathom Hospital, Nakornping Hospital, Phayao Provincial Hospital, Drapokklao Hospital, Samutprakarn Hospital, and Samutsakorn Hospital. This research aims to develop more effective ways of preventing HIV infection in children and to improve methods to treat HIV infected adults, adolescents and children. It will also strengthen the expertise of the health care workers participating in the research in Thailand, and the knowledge produced will improve the care given in all affected areas. ADMINISTRATIVE COMPONENT: